> ...WhatsApp isn't free. I have to spend hundreds of dollars upfront to buy a phone...
WhatsApp works reliably on a staggeringly broad list of devices. You can get a supported phone for, like, $20 and stick a $5-per-month prepaid SIM in it (many of these plans in low-income countries specifically come with WhatsApp allowances) and be connected.
WhatsApp is as effectively free as it can be within the segment of the population that needs or wants it.
This is like arguing that free Wi-Fi isn't "free" because some people only use ethernet. If you don't already own a compatible device, you aren't their customer anyway.
WhatsApp works reliably on a staggeringly broad list of devices. You can get a supported phone for, like, $20 and stick a $5-per-month prepaid SIM in it (many of these plans in low-income countries specifically come with WhatsApp allowances) and be connected.